Orally rapidly disintegrating tablets have been developed as a form which is easy to be taken by patients, elderly people, children, etc. who have difficulty in swallowing drugs, or is easy to be taken without water. The orally rapidly disintegrating tablets should have such a sufficient hardness as not being chipped or dusted during production or transportation of tablets or opening, and in addition, it is required that a disintegration time in the oral cavity is within about 60 seconds and a texture and taste in the oral cavity has no problem. There are more problems to be solved in the orally rapidly disintegrating tablets compared to normal tablets.
Specifically, a disintegration time and hardness are contradictory factors, and in general, disintegration times tend to be extended as molding pressures are increased for the purpose of the increase of hardness, and hardness tends to be decreased as molding pressures are decreased for the purpose of the shortening of disintegration times. Additionally, suppressing hardness degradations due to absorption of moisture is required upon opening in a room. Hardness degradations due to absorption of moisture tend to occur in orally disintegrating tablets, since the orally disintegrating tablets absorb water to disintegrate just after they have contact with water.
A quickly dispersible particle containing inorganic antiacid obtained by homogeneously dispersing an inorganic antiacid, a sugar alcohol and a disintegrant in aqueous medium which is rapidly dispersed and suspended upon being added in water (Patent Document 1), an orally rapidly disintegrating tablet comprising a pharmaceutical composition obtained by dispersing sugar and an inorganic compound in water and spray-drying (Patent Document 2), and a composition for an orally rapidly disintegrating tablet characterized by dispersing a disintegrant and an inorganic substance in complex particles of sugar in the presence of water (Patent Documents 3, 4, 5) have been known.
These conventional art documents disclose that particles obtained by dispersing and dissolving sugar, an inorganic substance and a disintegrant in water and spray-drying are used in an orally rapidly disintegrating tablet, but said orally rapidly disintegrating tablet has not had sufficient hardness (40N or more) during production and transportation, sufficient disintegrating properties in the oral cavity within 60 seconds, and has degraded in hardness under humid conditions after opening, etc. The conventional art documents do not disclose any disintegrating particle composition comprising mannitol, xylitol, an inorganic excipient, a disintegrant and carmellose, a process for preparing the same, and any orally rapidly disintegrating tablet comprising said composition.    [Patent document 1] JP-A-10-120554    [Patent document 2] JP-A-2000-86537    [Patent document 3] WO 2005/37319 pamphlet    [Patent document 4] WO 2005/37254 pamphlet    [Patent document 5] WO 2007/29376 pamphlet